Imaging apparatus, lens apparatus, and intermediate accessory

ABSTRACT

A lens apparatus is mountable to a camera body. The camera body has multiple electric contacts. Of these multiple electric contacts, when mounting the lens apparatus to the camera body, electric contacts used for second communication or third communication come into contact with an electric contact provided to the lens apparatus before electric contacts used for first communication, when mounting the lens apparatus to the camera body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/738,960, filed Jan. 9, 2020, which is a continuation of U.S. patentapplication Ser. No. 15/992,697, filed on May 30, 2018, now U.S. Pat.No. 10,602,038, which claims the benefit of Japanese Patent ApplicationNo. 2017-108256 filed May 31, 2017, all of which are hereby incorporatedby reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an imaging apparatus, a lens apparatus(lens device), and an intermediate accessory, that are capable ofcommunicating with each other.

Description of the Related Art

Accessory devices such as lens apparatuses that are detachably mountableto an imaging apparatus operate by receiving a supply of power from theimaging apparatus, communicating with the imaging apparatus, and soforth. Accordingly, multiple electric contacts are provided both on amount unit at the imaging apparatus and a mount unit at the accessorydevice. When an accessory device is mounted to the imaging apparatus,the electric contacts at the camera body side and the electric contactsat the accessory device side come into contact, and the imagingapparatus and the accessory device are electrically connected.

US2012/0063016 describes an imaging apparatus and lens apparatus wheretwo electric contact groups, which perform different communication fromeach other, are provided.

SUMMARY OF THE INVENTION

Generally, a lens apparatus and imaging apparatus are coupled by bayonetcoupling. Accordingly, when mounting the lens apparatus to the imagingapparatus, the electric contacts at the imaging apparatus side slideover the electric contacts at the lens apparatus side, and wear. Suchwear of the electric contacts can cause problems in communicationbetween the imaging apparatus and lens apparatus.

Since the amount of wear of electric contacts differs depending on theposition, it is preferable to decide the order of array of the electriccontacts in accordance with the role of each in communication, whenproviding multiple electric contacts to perform communication with alens apparatus by multiple communication methods, as with the imagingapparatus described in US2012/0063016.

It has been found desirable to reduce occurrence of poor communicationdue to wear of electric contacts of an imaging apparatus.

According to an aspect of the present invention, an imaging apparatus towhich a lens apparatus is detachably mountable includes a mount unitwhere a plurality of electric contacts are arrayed. The plurality ofelectric contacts include a first electric contact group used to performfirst communication with a lens apparatus mounted to the imagingapparatus, and a second electric contact group used to performcommunication that is different from the first communication with a lensapparatus mounted to the imaging apparatus. The imaging apparatus iscapable of mounting a first lens apparatus that is capable ofcommunication using the first electric contact group but not capable ofcommunication using the second electric contact group, and a second lensapparatus that is capable of communication using the first electriccontact group and communication using the second electric contact group.Where direction of movement of the lens apparatus with respect to theimaging apparatus when mounting the lens apparatus to the imagingapparatus is a first direction, the second electric contact group andthe first electric contact group are arrayed in the order of the secondelectric contact group and the first electric contact group in the firstdirection.

According to another aspect of the present invention, an imagingapparatus to which a lens apparatus is detachably mountable includes amount unit where a plurality of electric contacts are arrayed. Theplurality of electric contacts include a first electric contact groupused to perform first communication with a lens apparatus mounted to theimaging apparatus, and a second electric contact group used to performcommunication that is different from the first communication with a lensapparatus mounted to the imaging apparatus. The imaging apparatus iscapable of mounting a first lens apparatus that is capable ofcommunication using the first electric contact group but not capable ofcommunication using the second electric contact group, and a second lensapparatus that is capable of communication using the first electriccontact group and communication using the second electric contact group.The plurality of electric contacts are arrayed such that when the secondlens apparatus is mounted to the imaging apparatus, the second electriccontact group and an electric contact provided to the second lensapparatus come into contact before the first electric contact group andan electric contact provided to the second lens apparatus come intocontact.

According to another aspect of the present invention, an imagingapparatus to which a lens apparatus is detachably mountable includes amount unit where a plurality of electric contacts are arrayed. Theplurality of electric contacts include a first electric contactconfigured to be capable of outputting a clock signal, a second electriccontact configured to be capable of transmitting data to the lensapparatus synchronously with the clock signal, a third electric contactconfigured to be capable of receiving data transmitted synchronouslywith the clock signal, and a fourth electric contact configured to becapable of receiving data transmitted from the lens apparatus inaccordance with data transmitted from the second electric contact. Theplurality of electric contacts are arrayed such that when the lensapparatus is mounted to the imaging apparatus, the fourth electriccontact and an electric contact provided to the lens apparatus come intocontact before any one of the first through third electric contacts andan electric contact provided to the lens apparatus come into contact.

According to another aspect of the present invention, a lens apparatusdetachably mountable to an imaging apparatus includes a mount unit. Theimaging apparatus is capable of mounting a plurality of lens apparatusesincluding a first lens apparatus that is capable of communication usinga first electric contact group that is part of the plurality of electriccontacts provided to the imaging apparatus, but not capable ofcommunication using a second electric contact group that is differentfrom the first electric contact group, and a second lens apparatus thatis capable of communication using the first electric contact group andcommunication using the second electric contact group. The mount unit ofthe lens apparatus is configured to be capable of coupling with theimaging apparatus. A plurality of electric contacts including a thirdelectric contact group for performing communication with the imagingapparatus using the first electric contact group are provided to themount unit. The plurality of electric contacts at the lens side arearrayed such that when the lens apparatus is mounted to the imagingapparatus, an electric contact included in the third electric contactgroup comes into contact with an electric contact included in the firstelectric contact group after coming into contact with an electriccontact included in the second electric contact group.

According to another aspect of the present invention, a lens apparatusdetachably mountable to an imaging apparatus includes a mount unit. Theimaging apparatus includes a plurality of electric contacts including afirst electric contact configured to be capable of outputting a clocksignal, a second electric contact configured to be capable oftransmitting data synchronously with the clock signal, a third electriccontact configured to be capable of receiving data transmittedsynchronously with the clock signal, and a fourth electric contactconfigured to be capable of receiving data transmitted in accordancewith data transmitted from the second electric contact. A plurality ofelectric contacts including a fifth electric contact configured to becapable of receiving the clock signal, a sixth electric contactconfigured to be capable of receiving data transmitted from the imagingapparatus synchronously with the clock signal, and a seventh electriccontact configured to be capable of transmitting data to the imagingapparatus synchronously with the clock signal, are arrayed on the mountunit of the lens apparatus. The fifth through seventh electric contactsare arrayed on the mount unit such that, when mounting the lensapparatus to the imaging apparatus, the fifth through seventh electriccontacts come into contact with the first through third electriccontacts after coming into contact with the fourth electric contact.

According to another aspect of the present invention, an accessorycapable of being mounted between an imaging apparatus and a lensapparatus includes a mount unit. The imaging apparatus is capable ofmounting a plurality of lens apparatuses including a first lensapparatus that is capable of communication using a first electriccontact group that is part of the plurality of electric contactsprovided to the imaging apparatus, but not capable of communicationusing a second electric contact group that is different from the firstelectric contact group, and a second lens apparatus that is capable ofcommunication using the first electric contact group and communicationusing the second electric contact group. A plurality of electriccontacts, including a fourth electric contact group made up of anelectric contact that comes into contact with an electric contactincluded in the first electric contact group in a state where theaccessory is mounted to the imaging apparatus, are arrayed on the mountunit of the accessory. The electric contact included in the fourthelectric contact group is arrayed on the mount unit so as to come intocontact with an electric contact included in the first electric contactgroup after coming into contact with an electric contact included in thesecond electric contact group, when mounting the accessory to theimaging apparatus.

According to another aspect of the present invention, an accessorycapable of being mounted between an imaging apparatus and a lensapparatus includes a mount unit. The imaging apparatus includes aplurality of electric contacts including a first electric contactconfigured to be capable of outputting a clock signal, a second electriccontact configured to be capable of transmitting data synchronously withthe clock signal, a third electric contact configured to be capable ofreceiving data transmitted synchronously with the clock signal, and afourth electric contact configured to be capable of receiving datatransmitted in accordance with data transmitted from the second electriccontact. A plurality of electric contacts including an eighth electriccontact configured to come into contact with the first electric contactin a state of being mounted to the imaging apparatus, a ninth electriccontact configured to come into contact with the second electric contactin a state of being mounted to the imaging apparatus, and a tenthelectric contact configured to come into contact with the third electriccontact in a state of being mounted to the imaging apparatus, arearrayed on the mount unit of the accessory. When mounting the accessoryto the imaging apparatus, the eighth through tenth electric contacts arearrayed on the mount so as to come into contact with the first throughthird electric contacts after coming into contact with the fourthelectric contact.

According to another aspect of the present invention, a camera systemincludes an imaging apparatus and a lens apparatus configured to bedetachably mountable to the imaging apparatus. The imaging apparatusincludes a first mount unit on which are arrayed a plurality of electriccontacts, including a first electric contact group used to perform firstcommunication with the lens apparatus mounted to the imaging apparatus,and a second electric contact group used to perform communication thatis different from the first communication with a lens apparatus mountedto the imaging apparatus. The lens apparatus includes a second mountunit capable of coupling with the first mount unit, and on which arearrayed a plurality of electric contacts, including a third electriccontact group used to perform communication with the imaging apparatususing the first electric contact group. The imaging apparatus is capableof mounting a first lens apparatus that is capable of communicationusing the first electric contact group but not capable of communicationusing the second electric contact group, and a second lens apparatusthat is capable of communication using the first electric contact groupand communication using the second electric contact group. With adirection of movement of the lens apparatus as to the imaging apparatuswhen mounting the lens apparatus to the imaging apparatus as a firstdirection, the second electric contact group and the first electriccontact group are arrayed in the order of the second electric contactgroup and the first electric contact group in the first direction.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings. Each of the embodiments of the present inventiondescribed below can be implemented solely or as a combination of aplurality of the embodiments or features thereof where necessary orwhere the combination of elements or features from individualembodiments in a single embodiment is beneficial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram describing the mutual relation between an imagingapparatus, lens apparatus, and intermediate accessory device.

FIGS. 2A through 2D are schematic diagrams of mount units.

FIG. 3 is a block diagram of an imaging apparatus and lens apparatusaccording to an embodiment of the present invention.

FIGS. 4A and 4B are schematic diagrams of a camera-side contact holdingmember and an accessory-side contact holding member.

FIGS. 5A and 5B are block diagrams of an imaging apparatus, lensapparatus, and intermediate accessory device according to an embodimentof the present invention.

FIGS. 6A and 6B are block diagrams of the imaging apparatus andintermediate accessory device according to an embodiment of the presentinvention, and a lens apparatus according to a conventional arrangement.

FIGS. 7A through 7E are schematic diagrams of peripheral circuits of aTYPE terminal.

FIG. 8 is a flowchart illustrating an operation flow of the imagingapparatus when the lens apparatus is mounted.

FIG. 9 is a flowchart illustrating a second communication flow.

FIG. 10 is a diagram describing a broadcast communication mode in thirdcommunication.

FIG. 11 is a diagram describing a P2P communication mode in thirdcommunication.

FIGS. 12A and 12B are diagrams describing cases where a DGND terminaland a terminal adjacent to the DGND terminal short-circuit.

FIGS. 13A through 13C are diagrams describing cases where a LCLKterminal and a terminal adjacent to the LCLK terminal short-circuit.

DESCRIPTION OF THE EMBODIMENTS

Various types of terminology used in the specification of the presentapplication will be described prior to the description relating toembodiments of the present invention. The term “accessory apparatus(device)” refers to a device that is mountable to an imaging apparatus(image pick-up apparatus). The imaging apparatus and accessory deviceare mounted by coupling of mount units that each has. Accessory devicesinclude lens apparatuses (lens devices) having an image-taking opticalsystem. Accessory devices also include an intermediate accessory mountedbetween a lens apparatus and the imaging apparatus body.

The term “mount unit (portion)” is a coupling unit, provided to each ofthe imaging apparatus and accessory device. The mount unit of theimaging apparatus and the mount unit of the accessory device each areprovided with electric contacts (electric terminals) and the electriccontacts provided to the respective mount units come into contact whenthe accessory device is mounted to the imaging apparatus. That is tosay, the mount units not only serve to mechanically couple the imagingapparatus body and accessory device, but also to electrically connectthe imaging apparatus body and accessory device.

Next, the mutual relation between the imaging apparatus, lens apparatus,and intermediate accessory device according to an embodiment will bedescribed with reference to FIG. 1. FIG. 1 illustrates the mutualrelation among a camera body 100 serving as the imaging apparatusaccording to the present embodiment, a lens apparatus 200 according tothe present embodiment, intermediate accessory devices 400 and 500according to the present embodiment, and a lens apparatus 300 accordingto a conventional arrangement, which has a different configuration fromthe lens apparatus 200 according to the present embodiment. The arrowsin FIG. 1 indicate that the devices that can be mounted to each other bycoupling the respective mount units. The lens apparatus 200 has animage-taking optical system 280, and the lens apparatus 300 has animage-taking optical system 380. The camera body 100 has an imagingdevice such as a complementary metal-oxide semiconductor (CMOS) sensor,charge-coupled device (CCD) sensor, or the like. A subject can be takenby mounting the lens apparatus 200 or lens apparatus 300 on the camerabody 100.

The lens apparatus 200, intermediate accessory device 500, andintermediate accessory device 400 can be directly mounted to the camerabody 100. That is to say, a mount unit 250 of the lens apparatus 200, amount unit 550 a of the intermediate accessory device 500, and a mountunit 450 a of the intermediate accessory device 400, have shapes thattenable coupling to a mount unit 150 of the camera body 100.

The intermediate accessory device 500 also has, besides the mount unit550 a serving as a first accessory mount unit mountable to the camerabody 100, a mount unit 550 b serving as a second accessory mount unitthat has the same shape as the mount unit 150 of the camera body 100.Accordingly, the lens apparatus 200 can be mounted to the intermediateaccessory device 500 as well. In other words, the lens apparatus 200 canbe mounted to the camera body 100 via the intermediate accessory device500. Also note that another intermediate accessory device (omitted fromillustration) may be mounted between the lens apparatus 200 and theintermediate accessory device 500. In this case, two intermediateaccessory devices will be mounted between the lens apparatus 200 and thecamera body 100.

On the other hand, the shape of the mount unit 150 is such that a mountunit 350 of the lens apparatus 300 cannot be coupled thereto.Accordingly, the lens apparatus 300 cannot be directly mounted to thecamera body 100. However, the lens apparatus 300 can be mounted to thecamera body 100 via the intermediate accessory device 400 that has themount unit (first accessory mount unit) 450 a and mount unit (secondaccessory mount unit) 450 b that can be mounted to the lens apparatus300. Thus, any of multiple lens apparatuses including the lens apparatus200 and lens apparatus 300 are selectively mounted to the camera body100.

Next, the mount units of the camera body 100, lens apparatus 200, lensapparatus 300, intermediate accessory device 500, and intermediateaccessory device 400 will be described with reference to FIGS. 2Athrough 2D. FIG. 2A is a schematic diagram of the mount unit 150 of thecamera body 100 as viewed from the subject side, and FIG. 2B is aschematic diagram of the mount unit 250 of the lens apparatus 200 asviewed from the image plane side. FIG. 2C is a schematic diagram of themount unit 450 b of the intermediate accessory device 400 as viewed fromthe subject side, and FIG. 2D is a schematic diagram of the mount unit350 of the lens apparatus 300 as viewed from the image plane side.

The mount unit 150 is provided to the front side (subject side) of thecamera body 100. The mount unit 150 has a ring-shaped mount referenceface 151 for ensuring a predetermined flange focal distance. Threebayonet claws 152 a through 152 c are provided on the inner side of themount reference face 151 in the circumferential direction. A lock pin153 for positioning when bayonet-coupling the mount unit of an accessorydevice to the mount unit 150 is provided to the mount unit 150, so as tobe retractably protruding with regard to the mount reference face 151.When the mount unit 150 and the mount unit of an accessory device arerelatively rotated to a position where mounting is complete, the lockpin 153 engages a fitting hole provided to the mount unit of theaccessory device.

A camera-side contact holding member 154 is provided at a region furtheron the inner side from the bayonet claws 152 a through 152 c. Thecamera-side contact holding member 154 holds electric contacts(camera-side electric contacts) 1001 through 1012.

The mount unit 550 b of the intermediate accessory device 500 has thesame configuration as that of the mount unit 150 illustrated in FIG. 2A.

The mount unit 250 is fixed to the rear end (image plane side) of thelens apparatus 200. The mount unit 250 has a ring-shaped mount referenceface 251 that is a reference face for flange focal distance. Threebayonet claws 252 a through 252 c are provided on the inner side of themount reference face 251 in the circumferential direction. Further, afitting face 253 is provided to the mount unit 250. The lock pin 153fits to the fitting face 253 when mounting of the lens apparatus 200 tothe camera body 100 is complete. An accessory-side contact holdingmember 254 is provided at a region further on the inner side from thebayonet claws 252 a through 252 c. The accessory-side contact holdingmember 254 holds electric contacts (lens-side electric contacts) 2001through 2012.

The mount unit 550 a of the intermediate accessory device 500 and themount unit 450 a of the intermediate accessory device 400 have the sameconfiguration as the mount unit 250 illustrated in FIG. 2B. That is tosay, the mount unit 550 a of the intermediate accessory device 500 andthe mount unit 450 a of the intermediate accessory device 400 haveaccessory-side contact holding units that hold electric contacts(accessory side electric contact group) 2001 through 2012.

In the same way as the mount unit 150, the mount unit 450 has a mountreference face 451, bayonet claws 452 a through 452 c, and a contactholding member 454. Note however, that the length of the bayonet claws452 a through 452 c and the intervals between bayonet claws differs fromthat of the bayonet claws 152 a through 152 c of the mount unit 150.

In the same way as the mount unit 250, the mount unit 350 has a mountreference face 451, bayonet claws 352 a through 352 c, and a contactholding member 354. Note however, that the length of the bayonet claws352 a through 352 c and the intervals between adjacent bayonet clawsdiffers from that of the bayonet claws 252 a through 252 c of the mountunit 250.

Next, a case where the lens apparatus 200 is mounted to the camera body100 will be described with reference to FIG. 3. FIG. 3 is a blockdiagram illustrating a circuit configuration of a state where the lensapparatus 200 is mounted to the camera body 100. The lens apparatus 200and the camera body 100 can communicate via a communication path made upby part of the multiple electric contracts provided to the mount unit150 and mount unit 250. The lens apparatus 200 and the camera body 100can perform later-described first communication, second communication,and third communication. That is to say, the lens apparatus 200corresponds to a second lens apparatus.

A camera control unit 101 serving as a camera control unit controlscommunication performed between an accessory device mounted to thecamera body 100, by controlling output of electric contacts provided tothe mount unit 150, processing signals input to electric contacts, andso forth.

A camera power source unit 103 is a power source used to operate theparts of the camera body 100 and the accessory device mounted to thecamera body 100. The camera power source unit 103 generates multipledifferent voltages, and supplies power source of these voltages to theparts of the camera body 100 and the accessory device mounted to thecamera body 100.

A power source switching unit 104 supplies power source to a firstcommunication interface unit 102 a. The power source switching unit 104is supplied with power source of two different voltage values from thecamera power source unit 103, and can switch the power source to besupplied to the first communication interface unit 102 a, under controlof the camera control unit 101.

A lens control unit 201 serving as a lens control unit controlscommunication performed between the camera body 100 and the lensapparatus 200, by controlling output of electric contacts provided tothe mount unit 250, processing signals input to electric contacts, andso forth.

A lens power source unit 203 generates power source of a predeterminedvoltage from the power source supplied from the camera body 100, whichis supplied to the lens control unit 201 and a lens-side communicationinterface unit 202.

The electric contact 1001 and the electric contact 2001 are terminalsused to supply power, used for control of communication performedprimarily between the camera body 100 and lens apparatus 200(communication power), from the power source unit 103 of the camera body100 to the lens apparatus 200. Hereinafter, the electric contact 1001and electric contact 2001 may also be referred to as “VDD terminal 1001”and “VDD terminal 2001”. In the present embodiment, the voltage of powersupplied to the lens apparatus 200 by the VDD terminal 1001 (hereinafterreferred to as “VDD voltage”) is 5.0 V.

The electric contact 1002 and the electric contact 2002 are terminalsused to supply power, used primarily for operations of driving systemssuch as motors and the like (drive power), from the camera body 100 tothe lens apparatus 200. Hereinafter, the electric contact 1002 andelectric contact 2002 may also be referred to as “VBAT terminal 1002”and “VBAT terminal 2002”. In the present embodiment, the voltage ofpower supplied to the lens apparatus 200 by the VBAT terminal 1002(hereinafter referred to as “VBAT voltage”) is 4.5 V. The VDD terminalsand VBAT terminals may also be collectively referred to as “power sourcesystem terminals”.

The electric contact 1012 and the electric contact 2012 are terminalsthat ground communication control system circuits of the camera mainbody 100 and lens apparatus 200. That is to say, these are groundterminals corresponding to the VDD terminals. Hereinafter, the electriccontact 1012 and electric contact 2012 may also be referred to as “DGNDterminal 1012” and “DGND terminal 2012”.

The electric contact 1004 and the electric contact 2004 are terminalsthat ground drive system circuits including motors and so forth,provided to the camera main body 100 and lens apparatus 200. That is tosay, these are ground terminals corresponding to the VBAT terminals.Hereinafter, the electric contact 1004 and electric contact 2004 mayalso be referred to as “PGND terminal 1004” and “PGND terminal 2004”.The DGND terminals and PGND terminals may also be collectively referredto as “ground terminals”.

The electric terminal 1005 and the electric terminal 2005 are terminalsfor detecting that a lens apparatus has been mounted to the camera body100. The camera control unit 101 detects mounting and detaching of alens apparatus to and from the camera body 100 in accordance with thevoltage level of the electric contact 1005. When the camera control unit101 detects mounting of a lens apparatus, supply of power source to thelens apparatus via the VDD terminal 1001 and VBAT terminal 1002 isstarted. Hereinafter, the electric terminal 1005 and electric terminal2005 may be also referred to as “MIF terminal 1005” and “MIF terminal2005”.

The electric contact 1003 and the electric contact 2003 are terminalsfor distinguishing the type of accessory device mounted to the camerabody 100. The electric contact 1003 is pulled up to the same voltage asthe power source supplied to the camera control unit 101 within thecamera body 100, by a resistor 125. The electric contact 2003 is pulleddown to ground (DGND) via a resistor 222 within the lens apparatus 200.The camera control unit 101 detects the voltage value at the electriccontact 1003, and distinguishes the type of accessory device mounted tothe camera body 100 based on the detected voltage value. That is to say,the camera control unit 101 also functions as a distinguishing unit thatdistinguishes the type of accessory device mounted to the camera controlunit 101. The camera control unit 101 also controls the power sourceswitching unit 104 so that the power source supplied to the firstcommunication interface unit 102 a by the power source switching unit104 is switched in accordance with the type of accessory device mountedto the camera body 100. Accordingly, the camera body 100 and theaccessory device mounted to the camera body 100 can communicate at anappropriate communication voltage. Hereinafter, the electric contact1003 and electric contact 2003 may also be referred to as “TYPE terminal1003” and “TYPE terminal 2003”.

The electric contacts 1006 through 1008 and the electric contacts 2006through 2008 are terminals used for later-described first communication.The input/output of the electric contacts 1006 through 1008 iscontrolled by the camera control unit 101 via the first communicationinterface unit 102 a. The input/output of the electric contacts 2006through 2008 is controlled by the lens control unit 201 via thelens-side communication interface unit 202.

The electric contact 1008 (first camera-side electric contact, alsoreferred to as “first electric contact”) and the electric contact 2008(first lens-side electric contact, also referred to as “fifth electriccontact”) are terminals capable of output clock signals used for thefirst communication from the camera body 100 to the lens apparatus 200.The electric contact 1008 and electric contact 2008 are also used forthe lens apparatus 200 to notify the camera body 100 of a communicationstandby request. Hereinafter, the electric contact 1008 and electriccontact 2008 may also be referred to as “LCLK terminal 1008” and “LCLKterminal 2008”. The LCLK terminal 1008 is pulled up to the samepotential as the interface voltage of the first communication interfaceunit 102 a via a resistor 120 within the camera body 100. The LCLKterminal 2008 is pulled up to the same potential as the interfacevoltage of the lens-side communication interface unit 202 via a resistor220 within the lens apparatus 200.

The electric contact 1006 (second camera-side electric contact, alsoreferred to as “second electric contact”) and the electric contact 2006(second lens-side electric contact, also referred to as “sixth electriccontact”) are terminals capable of transmitting data from the camerabody 100 to the lens apparatus 200 by the first communication.Hereinafter, the electric contact 1006 and electric contact 2006 mayalso be referred to as “DCL terminal 1006” and “DCL terminal 2006”. TheDCL terminal 2006 is pulled up to the same potential as the interfacevoltage of the lens-side communication interface unit 202 via a resistor221 within the lens apparatus 200.

The electric contact 1007 (third camera-side electric contact, alsoreferred to as “third electric contact”) and the electric contact 2007(third lens-side electric contact, also referred to as “seventh electriccontact”) are terminals capable of transmitting data from the lensapparatus 200 to the camera body 100 by the first communication.Hereinafter, the electric contact 1007 and electric contact 2007 mayalso be referred to as “DLC terminal 1007” and “DLC terminal 2007”. TheDLC terminal 1007 is pulled up to the same potential as the interfacevoltage of the first communication interface unit 102 a via a resistor121 within the camera body 100.

Hereinafter, the LCLK terminal 1008, DCL terminal 1006, and DLC terminal1007, used in the first communication, may also be referred to as “firstcamera-side electric contact group” or “first electric contact group”.Also, the LCLK terminal 2008, DCL terminal 2006, and DLC terminal 2007,used in the first communication, may also be referred to as “firstlens-side electric contact group” or “third electric contact group”.DLC2 terminal 1009, DCA terminal 1010, and CS terminal 1011, which areelectric contacts used for communication that differs from the firstcommunication i.e., second communication and third communication, mayalso be referred to as “second camera-side electric contact group” or“second electric contact group”.

The electric contact 1009 (fourth camera-side electric contact, alsoreferred to as “fourth electric contact”) and electric contact 2009 areused in later-described second communication. The electric contact 1009and electric contact 2009 are terminals capable of transmitting datafrom the lens apparatus 200 to the camera body 100 by the secondcommunication. Hereinafter, the electric contact 1009 and electriccontact 2009 may also be referred to as “DLC2 terminal 1009” and “DLC2terminal 2009”. The DLC2 terminal 1009 is pulled down to the samepotential as the DGND terminal via a resistor 122 within the camera body100.

The electric contacts 1010 and 1011, and the electric contacts 2010 and2011, are terminal used in later-described third communication. Theelectric contact 1010 and the electric contact 2010 are terminalscapable of bi-directionally exchanging data between the camera body 100and lens apparatus 200 by the third communication. Hereinafter, theelectric contact 1010 and electric contact 2010 may also be referred toas “DCA terminal 1010” and “DCA terminal 2010”. The DCA terminal 1010 ispulled up to the same potential as the interface voltage as thesecond/third communication interface unit 102 b via a resistor 124within the camera body 100. The DCA terminal 1010 is connected to thecamera control unit 101 via a CMOS-type input/output interface. In thesame way, the DCA2 terminal 2010 is connected to the lens control unit201 via a CMOS-type input/output interface. Accordingly, the cameracontrol unit 101 and the lens control unit 201 can exchange data at highspeeds, using the DCA terminals 1010 and 2010.

The electric contact 1011 and the electric contact 2011 are terminalsused in notification of a later-described predetermined timing relatingto third communication between the camera body 100 and lens apparatus200. Hereinafter, the electric contact 1011 and electric contact 2011may also be referred to as “CS terminal 1011” and “CS terminal 2011”.The CS terminal 1011 is pulled up to the same potential as the interfacevoltage of the second/third communication interface unit 102 b via aresistor 123 within the camera body 100. Also, the CS terminal 2011 ispulled up to the same potential as the interface voltage of thelens-side communication interface unit 202 via a resistor 224 within thelens apparatus 200. The CS terminal 1011 is connected to the cameracontrol unit 101 via an open-type output interface. In the same way, theCS terminal 2011 is connected to the lens control unit 201 via anopen-type output interface. Note that the term “open-type outputinterface” here means an output interface that is an open drain or anopen collector.

In a case where the lens apparatus 200 is mounted to the camera body 100in the present embodiment, the interface voltages of the firstcommunication interface unit 102 a and second/third communicationinterface unit 102 b are set to 3.0 V (first voltage). The interfacevoltage of the lens-side communication interface unit 202 is also set to3.0 V (first voltage). Note that hereinafter, the LCLK terminals, DCLterminal, DLC terminals, DCL2 terminals, CS terminals and DCA terminals,may be collectively referred to as “communication system terminals”.

Next, the shapes of the camera-side contact holding member 154 and theaccessory-side contact holding member 254 of the mount unit 150 andmount unit 250 will be described with reference to FIGS. 4A and 4B. FIG.4A is a schematic diagram viewing the camera-side contact holding member154 and accessory-side contact holding member 254 from a directionperpendicular to the optical axis, in a state where the lens apparatus200 is mounted to the camera body 100. FIG. 4B is a schematic diagramviewing the camera-side contact holding member 154 and accessory-sidecontact holding member 254 from a direction perpendicular to the opticalaxis, in a state where the lens apparatus 200 is not completely mountedto the camera body 100. FIGS. 4A and 4B illustrate the camera-sidecontact holding member 154 and accessory-side contact holding member 254in planar view. However, in reality, the shapes of the camera-sidecontact holding member 154 and accessory-side contact holding member 254are curved following the circumferential direction of the mount unit 150and mount unit 250. Although the electric contacts of the camera body100 are illustrated in FIGS. 4A and 4B as being pins and the electriccontacts of the lens apparatus 200 as being contact pieces, anarrangement may be made where the electric contacts of the camera body100 are contact pieces and the electric contacts of the lens apparatus200 are pins.

Arrow A illustrated in FIG. 4A indicates the direction in which the lensapparatus 200 moves as to the camera body 100 (rotation direction) whendetaching the lens apparatus 200 from the camera body 100. Whendetaching the lens apparatus 200, the VDD terminal 2001 for examplecomes into contact with the TYPE terminal 1003 after having come intocontact with the VBAT terminal 1002.

Also, arrow B illustrated in FIG. 4B indicates the direction in whichthe lens apparatus 200 moves as to the camera body 100 (rotationdirection) when mounting the lens apparatus 200 to the camera body 100.The direction of arrow B corresponds to a first direction. When mountingthe lens apparatus 200, the VDD terminal 2001 for example is connectedto the VDD terminal 1001 after having come into contact with the VBATterminal 1002.

Also, the camera-side contact holding member 154 and the accessory-sidecontact holding member 254 have shapes that are stepped in the opticalaxis direction, as illustrated in FIGS. 4A and 4B. The electric contacts1001 through 1004 and the electric contacts 1005 through 1012 areprovided on different tiers (or steps). In the same way, the electriccontacts 2001 through 2004 and the electric contacts 2005 through 2012are provided on different tiers (or steps). Accordingly, the electriccontacts 2001 through 2004 can be kept from coming into contact with theelectric contacts 1005 through 1012 when mounting the lens apparatus 200to the camera body 100. Accordingly, the amount of wear of the electriccontacts when mounting/detaching the lens apparatus 200 to/from thecamera body 100 can be reduced.

Further, the camera body 100 according to the present embodiment haspower source system terminals on the tier that has fewer electriccontacts. In the same way, the lens apparatus 200 according to thepresent embodiment has power source system terminals on the tier thathas fewer electric contacts. Accordingly, the amount of wear of thepower source system terminals when mounting/detaching the lens apparatus200 to/from the camera body 100 can be further reduced, and increase incontact impedance can be suppressed. As a result, stable power sourcesupply can be performed over a long time. Further note that the groundterminals also are preferably provided on the tier that has fewerelectric contacts for stable power supply.

On the other hand, the DGND terminal 1012 and DGND terminal 2012 arepreferably brought into contact with a metal portion of the mount unit150 and mount unit 250, in order to reduce the influence of staticelectricity on the internal circuits. In this case, the DGND terminal1012 is preferably situated at the end of the array of electric contacts1001 through 1012, in order to facilitate forming of the mount unit 150.In the same way, the DGND terminal 2012 is preferably situated at theend of the array of electric contacts 2001 through 2012, in order tofacilitate forming of the mount unit 250.

In light of this, the PGND terminal 1004 is provided on the tier thatholds fewer electric contacts, and the DGND terminal 1012 is provided atthe end of the array of electric contacts 1001 through 1012 in thepresent embodiment. In the same way, the PGND terminal 2004 is providedon the tier that holds fewer electric contacts, and the DGND terminal2012 is provided at the end of the array of electric contacts 2001through 2012.

Next, the order of the array of the electric contacts on the camera-sidecontact holding member 154 and accessory-side contact holding member 254will be described. In the present embodiment, the PGND terminal 1004,TYPE terminal 1003, VBAT terminal 1002, and VDD terminal 1001 aredisposed on the tier of the camera-side contact holding member 154 thatholds fewer electric contacts, in order of the mounting direction of thelens apparatus 200 (direction of arrow B in FIG. 4B). In the same way,the PGND terminal 2004, TYPE terminal 2003, VBAT terminal 2002, and VDDterminal 2001 are disposed on the tier of the accessory-side contactholding member 254 that holds fewer electric contacts, in order of themounting direction of the lens apparatus 200 (direction of arrow B inFIG. 4B).

If an electroconductive foreign substance is caught between thecamera-side contact holding member 154 and accessory-side contactholding member 254, or an electric contact is deformed, adjacentelectric contacts may short-circuit each other. Particularly, in a casewhere the power source system terminals (VDD terminals and VBATterminals) short-circuit with the ground terminals (PGND terminals), alarge electric current will flow to the power source circuit. To counterthis, the influence of short-circuiting on the power source circuit canbe reduced by providing different electric contacts between the powersource system terminals and ground terminals.

Note that the terminals provided between the power source systemterminals and ground terminals preferably are terminals that have agenerally constant signal level during operations of the camera body 100and lens apparatus 200. Normally, a protective element, for protectinginternal circuits of the camera body 100 when short-circuiting occurs,is provided between the terminals adjacent to the power source systemterminals and the camera control unit 101. In a case where terminals ofwhich the signal level changes during operations of the camera body 100and lens apparatus 200, such as communication system terminals, areprovided between the power source system terminals and ground terminals,the wiring capacitance of these terminals will increase due to theprotective element. Accordingly, the signal waveforms transmitted orreceived through these terminals can be affected. On the other hand,terminals that have a generally constant signal level during operationsof the camera body 100 and lens apparatus 200 will be affected less byproviding the protective element. The TYPE terminals and MIF terminalsare terminals that have a generally constant signal level duringoperations, but the MIF terminals are preferably provided to the tierwhere there are more electric contacts, which will be described later,so the TYPE terminals are preferably provided between the power sourcesystem terminals and ground terminals. Note that a resistor 126 isdisposed between the TYPE terminal 1003 and the camera control unit 101as the protective element in the present embodiment.

The MIF terminal 1005 is disposed on the tier of the camera-side contactholding member 154 that has a greater number of electric contacts, at aposition that is closest to the tier with fewer electric contacts, inthe present embodiment. In a corresponding manner, the MIF terminal 2005is disposed on the tier of the accessory-side contact holding member 254that has a greater number of electric contacts, at a position that isclosest to the tier with fewer electric contacts.

Disposing the MIF terminal 1005 at this position enables the MIFterminal 2005 to be the only electric contact coming into contact withthe MIF terminal 1005 when attaching/detaching the lens apparatus 200to/from the camera body 100. Accordingly, the wear on the MIF terminal1005 can be reduced. This makes defective contact of the MIF terminal1005 less readily to occur, and whether the lens apparatus is mountedcan be appropriately detected.

Note that when attaching/detaching the lens apparatus 200 to/from thecamera body 100, the MIF terminal 2005 comes into contact with theelectric contacts 1006 through 1012, so it can be said that the MIFterminal 2005 is disposed at a position where the amount of wear due tosliding is great. However, multiple types of camera accessories aremounted to the camera body 100, as illustrated in FIG. 1, and so theamount of wear of the electric contacts on the lens apparatus 200 issmall as compared to that of the camera body 100. Accordingly, theelectric contacts are arrayed in the present embodiment so that theamount of wear of the MIF terminal 1005 of the camera body 100 is small.

Further, if the MIF terminal 1005 comes into contact with other electriccontacts when mounting the lens apparatus 200 to the camera body 100,the voltage level of the MIF terminal 1005 may change and the cameracontrol unit 101 may falsely detect mounting of the lens apparatus. Ifthere is false detection of the lens apparatus 200 before mounting ofthe lens apparatus 200 is complete, power source supply by the powersource system terminals may be started, which can lead to malfunctioningof the lens apparatus 200 and affect internal circuits of the lensapparatus 200. Conversely, disposing the MIF terminal 1005 as in thepresent embodiment enables starting of power source supply before theMIF terminals are connected to each other (before completion of mountingof the lens apparatus 200) to be suppressed.

Note that the length of the MIF terminal 2005 of the lens apparatus 200in the circumferential direction of the mount unit 250 preferably isshorter than that of the other electric contacts. Accordingly, whenmounting the lens apparatus 200 to the camera body 100, the MIF terminal2005 can be made to be connected last of the multiple electric contacts.In this case, power source supply from the camera body 100 to the lensapparatus 200 can be performed after connection of the other electriccontacts has been completed. Also, when detaching the lens apparatus 200from the camera body 100, the MIF terminal 2005 can be disengaged firstout of the multiple electric contacts. In this case, supply of powersource from the camera body 100 to the lens apparatus 200 can beimmediately stopped when detaching the lens apparatus 200 from thecamera body 100. Note that it is sufficient for the length of the MIFterminal 2005 in the circumferential direction of the mount unit 250 tobe shorter than the other electric contacts by an amount equivalent of 1degree center angle.

The order of the array of the communication system terminals in thepresent embodiment is appropriately decided, taking into considerationthe roles of the terminals. Specifically, the CS terminal 1011 isdisposed adjacent to the DGND terminal 1012, and the DCA terminal 1010is disposed on the other side of the CS terminal 1011 from the DGNDterminal 1012. In the same way, the CS terminal 2011 is disposedadjacent to the DGND terminal 2012, and the DCA terminal 2010 isdisposed on the other side of the CS terminal 2011 from the DGNDterminal 2012. Accordingly, electrical influence on the camera body 100and lens apparatus 200 from unintentional connection among electriccontacts with each other is reduced, while increasing the communicationspeed of the third communication, which will be described later.

Also, the DLC2 terminal 1009 used for second communication is providedbetween the DCA terminal 1010 and the LCLK terminal 1008. In the sameway, the DLC2 terminal 2009 used for second communication is providedbetween the DCA terminal 2010 and the LCLK terminal 2008. Accordingly,electrical influence on the camera body 100 and lens apparatus 200 fromunintentional connection among electric contacts with each other isreduced, which will be described later.

Further, the CS terminal 1011, DCA terminal 1010, DLC2 terminal 1009,and the first camera-side electric contact group, are disposed in thisorder in the first direction (direction of arrow B) on the camera-sidecontact holding member 154. That is to say, the amount of sliding thatthe electric contacts in the first camera-side electric contact groupexperience due to attaching/detaching of the accessory device is smallerthan that at any of the CS terminal 1011, DCA terminal 1010, and DLC2terminal 1009. Accordingly, defective communication due to wear of theelectric contacts is reduced, which will be described later.

Next, a case of mounting the lens apparatus 200 to the camera body 100via the intermediate accessory device 500 will be described withreference to FIGS. 5A and 5B. The intermediate accessory device 500 canperform third communication with the camera body 100.

FIGS. 5A and 5B are block diagrams illustrating a case of the lensapparatus 200 being mounted to the camera body 100 via the intermediateaccessory device 500. The intermediate accessory device 500 has themount unit 550 a and mount unit 550 b, as described earlier. Theintermediate accessory device 500 also has an accessory control unit 501that controls communication with the camera body 100 and performsprocessing in accordance with operation of an operating member (omittedfrom illustration) provided to the intermediate accessory device 500.Operation of the operating member is communicated to the accessorycontrol unit 501 via an adapter operation input unit 502. An example ofan operating member is a function ring by which the aperture value canbe set.

The mount unit 550 a is the same as the above-described mount unit 250of the lens apparatus 200. Accordingly, in a state where theintermediate accessory device 500 has been mounted to the camera body100, the electric contacts 2001 through 2012 provided to the mount unit550 a are in contact with the electric contacts 1001 through 1012provided to the camera body 100. The mount unit 550 b also is the sameas the above-described mount unit 150 of the camera body 100.Accordingly, in a state where the lens apparatus 200 is mounted to theintermediate accessory device 500, the electric contacts 1001 through1012 provided to the mount unit 550 b come into contact with theelectric contacts 2001 through 2012 provided to the lens apparatus 200.The electric contacts 2001 through 2012 provided to the mount unit 550 aare connected to the electric contacts 1001 through 1012 provided to themount unit 550 b by wiring within the intermediate accessory device 500.

Note that in the intermediate accessory device 500, the VDD terminal2001 is also connected to an accessory power supply unit 503, and isconfigured so as to supply electric power to the intermediate accessorydevice 500 as well. In the present embodiment, the accessory powersupply unit 503 generates power source of 3.0 V, and supplies to theaccessory control unit 501 and adapter operation input unit 502. The DCAterminal 2010 and CS terminal 2011 used for the third communicationwithin the intermediate accessory device 500 are also connected to theaccessory control unit 501, so the intermediate accessory device 500 andcamera body 100 can perform the third communication.

In a case where the lens apparatus 200 is mounted to the camera body 100via the intermediate accessory device 500, the interface voltage of thefirst communication interface unit 102 a and second/third communicationinterface unit 102 b is set to 3.0 V. The interface voltage of thelens-side communication interface unit 202 also is set to 3.0 V. This sofar has been a description of a case where the lens apparatus 200 ismounted to the camera body 100.

Next, a case of mounting the lens apparatus 300 to the camera body 100will be described with reference to FIGS. 6A and 6B. The lens apparatus300 is a lens apparatus according to a conventional arrangement, asmentioned earlier, and differs from the lens apparatus 200 according tothe present embodiment. The lens apparatus 300 cannot perform the secondcommunication or the third communication with the camera body, but canperform the first communication. That is to say, the lens apparatus 300corresponds to a first lens apparatus. The intermediate accessory device400 can perform the third communication with the camera body.

FIGS. 6A and 6B are block diagrams illustrating a case of the lensapparatus 300 being mounted to the camera body 100 via the intermediateaccessory device 400. As described above, the intermediate accessorydevice 400 has the mount units 450 a and 450 b. The intermediateaccessory device 400 also has an adapter control unit 401 that performsprocessing communication with the camera body 100, and processing inaccordance with operations made at an operating member omitted fromillustration. Operations at the operating member are notified to theadapter control unit 401 via an adapter operation input unit 402.

The mount unit 450 a is the same as the mount unit 250 of the lensapparatus 200. Note however, that the internal circuits of theintermediate accessory device 400 and the internal circuits of the lensapparatus 200 are different. Specifically, the DCL terminal 2006, DLCterminal 2007, and LCLK terminal 2008, used for the first communication,are not connected to the adapter control unit 401 within theintermediate accessory device 400, and are connected to thecorresponding electric contacts of the mount unit 450 b by throughwiring. On the other hand, the DCA terminal 2010 and CS terminal 2011used for the third communication are connected to the adapter controlunit 401 within the intermediate accessory device 400. This is in orderto perform the third communication between the intermediate accessorydevice 400 and camera body 100, and not perform the first communication.

The DLC2 terminal 2009 used for the second communication is pulled downto the same level as the DGND terminal 2012 via resistance within theintermediate accessory device 400. This is because the lens apparatus300 and camera body 100 do not perform the second communication.

The TYPE terminal 2003 also is pulled down to the same level as the DGNDterminal 2012 by a resistor 422 within the intermediate accessory device400. The resistor 422 has a resistance value that is different from thatof the resistor 222 of the lens apparatus 200.

Next the electric contacts provided to the mount unit 450 b and themount unit 350 will be described. An electric contact 3001 and anelectric contact 4001 are terminals used to supply driving power fromthe VBAT terminal 1002 of the camera body 100 to the lens apparatus 300.The VBAT terminal 2002 is connected to the electric contact 4001 bythrough wiring within the intermediate accessory device 400.Hereinafter, the electric contact 3001 and electric contact 4001 mayalso be referred to as “VBAT terminal 3001” and “VBAT terminal 4001”.Note that in the present embodiment, the voltage of power supplied tothe lens apparatus 300 by the VBAT terminal 1002 is 4.5 V.

An electric contact 3004 and an electric contact 4004 are terminals usedto supply communication power from the VDD terminal 1001 of the camerabody 100 to the lens apparatus 300. The VDD terminal 2001 is connectedto the electric contact 4001 by through wiring within the intermediateaccessory device 400, and also is connected to an adapter power source403 within the intermediate accessory device 400. The adapter powersource 403 generates a power source of 3.0 V as a power source to supplyto the adapter control unit 401 and the adapter operation input unit.Hereinafter, the electric contact 3004 and electric contact 4004 mayalso be referred to as “VDD terminal 3004” and “VDD terminal 4004”. Notethat in the present embodiment, the voltage of power supplied to thelens apparatus 200 by the VDD terminal 1001 is 5.0 V.

An electric contact 3003 and an electric contact 4003 are terminals usedto ground the driving systems of the camera body 100 and lens apparatus300. That is to say, these are ground terminals corresponding to theVBAT terminals. The PGND terminal 2004 is connected to the electriccontact 4003 by through wiring within the intermediate accessory device400. Hereinafter, the electric contact 3003 and electric contact 4003may also be referred to as “PGND terminal 3003” and “PGND terminal4003”.

An electric contact 3008 and an electric contact 4008 are terminals usedto ground the communication systems of the camera body 100 and lensapparatus 300. That is to say, these are ground terminals correspondingto the VDD terminals. The VDD terminal 2012 is connected to the electriccontact 4008 by through wiring within the intermediate accessory device400. Hereinafter, the electric contact 3008 and electric contact 4008may also be referred to as “DGND terminal 3008” and “DGND terminal4008”.

An electric contact 3002 and an electric contact 4002 are terminals usedto detect that the lens apparatus 300 has been mounted to the camerabody 100 via the intermediate accessory device 400. Upon detecting thatthe lens apparatus 300 has been mounted, the camera control unit 101starts supplying power source to the lens apparatus 300. The MIFterminal 2005 is connected to the electric contact 4002 by throughwiring in the intermediate accessory device 400. Hereinafter, theelectric contact 3002 and electric contact 4002 may also be referred toas MIF terminal 3002 and MIF terminal 4002.

Electric contacts 3005 through 3007 and electric contacts 4005 through4007 are terminals used for the later-described first communication. Theinput/output of the electric contacts 3005 through 3007 is controlled bya lens control unit 301 via a lens-side communication interface unit302. Hereinafter, the electric contacts 3005, 3006, and 3007 may also bereferred to as DCL terminal 3005, DLC terminal 3006, and LCLK terminal3007. The electric contacts 4005, 4006, and 4007 may also be referred toas DCL terminal 4005, DLC terminal 4006, and LCLK terminal 4007.

In a case where the lens apparatus 300 is mounted via the intermediateaccessory device 400, the interface voltages of the first communicationinterface unit 102 a and the lens-side communication interface unit 302are set to 5.0 V (second voltage) that is the same as the voltagesupplied from the VDD terminals. The second voltage is a voltage that isdifferent from the first voltage.

On the other hand, the interface voltage of the second/thirdcommunication interface unit 102 b is set to 3.0 V. That is to say, in acase where the lens apparatus 300 is mounted to the camera body 100 viathe intermediate accessory device 400, the communication voltage of thefirst communication and the communication voltage of the thirdcommunication are different from each other. In a case where the lensapparatus 300 is mounted to the camera body 100 via the intermediateaccessory device 400, the second communication is not performed, whichwill be described later.

This so far has been a description of the configuration of the camerabody 100 and of accessory devices that can be mounted to the camera body100. Next, the function of the TYPE terminal 1003 will be described indetail.

An assumption will be made in the following description that the powersource voltage the TYPE terminal 1003 is pulled up to within the camerabody 100 is 3.3 V. Assumption will also be made that the resistancevalue of the resistor 125 is 100 kΩ, the resistance value of theresistor 126 is 1 kΩ, the resistance value of the resistor 222 is 33 kΩ,and the resistance value of the resistor 422 is 300 kn. The voltagevalue input to a TYPE_IN terminal is converted into digital signals of10-bit resolution by an AD converter that is omitted from illustration.

FIG. 7A is an illustration of peripheral circuits of the TYPE terminal1003 in a state where the lens apparatus 200 is mounted to the camerabody 100. In this case, the value input to the TYPE_IN terminal of thecamera control unit 101 is a value where the power source voltage (3.3V) has been divided by the resistor 125 and resistor 222 and A-to-Dconverted, and is approximately “0x0103”.

Also, FIG. 7B is an illustration of peripheral circuits of the TYPEterminal 1003 in a state where the lens apparatus 300 is mounted to thecamera body 100 via the intermediate accessory device 400. In this case,the value input to the TYPE_IN terminal of the camera control unit 101is a value where the power source voltage (3.3 V) has been divided bythe resistor 125 and resistor 422 and A-to-D converted, and isapproximately “0x0300”.

Thus, the value input to the TYPE_IN terminal can be made to differ inaccordance with the type of accessory device mounted to the camera body100, by differing the resistance values of the resistor 422 of theintermediate accessory device 400 and the resistance value of theresistor 222 of the lens apparatus 200. Accordingly, the camera controlunit 101 can distinguish the type of accessory device mounted to thecamera body 100 using the value input to the TYPE_IN terminal.

However, in a case where there is some sort of abnormality that hasoccurred with regard to the connection state of the TYPE terminal 1003and the TYPE terminals 2003, an unanticipated value may be input to theTYPE_IN terminal. If the camera control unit 101 determines that thereis some sort of accessory device mounted to the camera body 100regardless of some sort of abnormality occurring in the mounting stateof the accessory device, nonrated voltage may be applied to theaccessory device, which should be avoided. Accordingly, a case wheresome sort of abnormality occurs with regard to the connection state ofthe TYPE terminal 1003 and the TYPE terminals 2003 will be consideredwith reference to FIGS. 7C through 7E.

FIG. 7C is an illustration of peripheral circuits of the TYPE terminal1003 in a state where the TYPE terminal 1003 and TYPE terminal 2003 arenot in contact, even though mounting of the accessory device to thecamera body 100 has been completed, due to faulty contact or the like.In this case, the voltage value input to the TYPE_IN terminal is decidedby the resistor 125 (100 kΩ) in the camera body 100 alone, and the valueafter A-to-D conversion is approximately “0x03FF”.

FIG. 7D is an illustration of peripheral circuits of the TYPE terminal1003 in a state where the TYPE terminal 1003 and the VBAT terminal 1002have short-circuited. A case will be considered here where determinationof the type of accessory device mounted to the camera body 100 isperformed before supply of power source to the VBAT terminal 1002 andVBAT terminal 2002. In a case where the voltages of the VBAT terminal1002 and VBAT terminal 2002 when power source is not being supplied arethe same as that of the PGND terminals, the voltage of the TYPE terminal1003 becomes generally equal to the voltage of the PGND terminals whenthe TYPE terminal 1003 and VBAT terminal 1002 short-circuit. At thistime, the value input to the TYPE_IN terminal is decided by the ratio ofvoltage dividing by the resistor 125 (100 kΩ) and the resistor 126 (1kΩ) within the camera body 100, and is approximately “0x000A”.

Next, a case will be considered where determination of the type of theaccessory device mounted to the camera body 100 is performed aftersupply of power source to the VBAT terminal 1002 and VBAT terminal 2002.In this case, if the TYPE terminal 1003 and the VBAT terminal 1002short-circuit, VBAT voltage (4.5 V in the present embodiment) will beapplied to the TYPE terminal 1003. The value input to the TYPE_INterminal at this time is approximately “0x03FF”.

FIG. 7E is an illustration of peripheral circuits of the TYPE terminal1003 in a state where the TYPE terminal 1003 and the PGND terminal 1004have short-circuited. In a case where the TYPE terminal 1003 and thePGND terminal 1004 have short-circuited, the voltage of the TYPEterminal 1003 is approximately equal to the voltage of the PGND terminal1004 (voltage of the reference potential for VBAT voltage). At thistime, the value input to the TYPE_IN terminal is decided by the ratio ofvoltage dividing by the resistor 125 (100 kΩ) and the resistor 126 (1kΩ) within the camera body 100, and is approximately “0x000A”.

As described above, in a case where some sort of abnormality occurs inthe connection state of the TYPE terminal 1003 and TYPE terminal 2003,the voltage of the TYPE terminal 1003 becomes generally equal to theVBAT voltage or the voltage of the PGND terminal 1004. Accordingly, therange of voltage of the TYPE terminal 1003 where determination is madein the present embodiment that a lens apparatus is properly mounted tothe camera body 100 is set to a voltage range that does not include theVBAT voltage and the voltage of the PGND terminal 1004. The Table belowis a correlation table of input values of the TYPE terminal and resultsof the camera control unit 101 distinguishing states of mounting.

TABLE 0x0000 0x0080 0x0180 0x0280 0x0380 through through through throughthrough TYPE_IN 0x007F 0x017F 0x027F 0x037F 0x03FF Determination ErrorLens — Lens Error results apparatus 200 apparatus 300 Communication —3.0 V — 5.0 V — voltage

It can be seen from the Table that the camera control unit 101determines the lens apparatus 200 to be mounted to the camera body 100if the input value of the TYPE_IN terminal is in the range of “0x0080through 0x017F”. This range “0x0080 through 0x017F” does not include theinput value of the TYPE_IN terminal in a case where the voltage of theTYPE terminal 1003 is the VBAT voltage or the voltage of the PGNDterminal 1004. Accordingly, the camera control unit 101 can determinethat the lens apparatus 200 has been mounted to the camera body 100 onlyin a case where the lens apparatus 200 has been properly mounted to thecamera body 100. In a case of having determined that the lens apparatus200 has been mounted, the camera control unit 101 performs communicationwith the lens apparatus 200 using communication voltage 3.0 V.

In the same way, the camera control unit 101 determines the lensapparatus 300 to be mounted to the camera body 100 if the input value ofthe TYPE_IN terminal is in the range of “0x0280 through 0x037F”. Thisrange “0x0280 through 0x037F” does not include the input value of theTYPE_IN terminal in a case where the voltage of the TYPE terminal 1003is the VBAT voltage or the voltage of the PGND terminal 1004.Accordingly, the camera control unit 101 can determine that the lensapparatus 300 has been mounted to the camera body 100 only in a casewhere the lens apparatus 300 has been properly mounted to the camerabody 100. In a case of having determined that the lens apparatus 300 hasbeen mounted, the camera control unit 101 performs communication withthe lens apparatus 300 using communication voltage 5.0 V. Thus,determining the correlation between the input values of the TYPE_INterminal and the results of the camera control unit 101 determining thestate of mounting enables the type of mounted lens apparatus to beappropriately distinguished.

On the other hand, the camera control unit 101 determines that some sortof abnormality is occurring with regard to the mounting state of thecamera body 100 and the accessory device if the input value of theTYPE_IN terminal is in the range of “0x0000 through 0x007F”. This range“0x0000 through 0x007F” includes the input value of the TYPE_IN terminal“0x000A” in a case where the voltages of the TYPE terminal 1003 and thePGND terminal 1004 are generally equal. In this case, the camera controlunit 101 does not communicate with the lens apparatus mounted to thecamera body. Thus, nonrated voltage can be prevented from being appliedto the accessory device in a case where an abnormality has occurred inthe connection state of the TYPE terminal.

Again, the camera control unit 101 determines that some sort ofabnormality is occurring with regard to the mounting state of the camerabody 100 and the accessory device if the input value of the TYPE_INterminal is in the range of “0x0380 through 0x03FF”. This range “0x0380through 0x03FF” includes the input value of the TYPE_IN terminal“0x03FF” in a case where the voltage of the TYPE terminal 1003 and theVBAT voltage are generally equal. In this case, the camera control unit101 does not communicate with the lens apparatus mounted to the camerabody. Thus, nonrated voltage can be prevented from being applied to theaccessory device in a case where an abnormality has occurred in theconnection state of the TYPE terminal.

Next, an operation flow of the camera body 100 will be described withreference to the flowchart in FIG. 8. This flow is carried out followinga computer program stored in the camera control unit 101. The flowchartin FIG. 8 starts from a state where the power source of the camera body100 is turned on by operation of a power switch of the camera body 100that is omitted from illustration. Note that steps in the flowchart areindicated by “S”.

First, the camera control unit 101 obtains the voltage value of anMIF_IN terminal in S601, and stores this in a random access memory (RAM)region that is omitted from illustration.

Next, in S602, the camera control unit 101 determines whether or not thevoltage value of the MIF_IN terminal stored in S601 is at a Low level.In a case where the voltage value of the MIF_IN terminal is not at theLow level, no lens apparatus is mounted to the camera body 100, so theflow returns to S601 (No in S602). In a case where the voltage value ofthe MIF_IN terminal is at the Low level, determination is made that alens apparatus is mounted to the camera body 100, and the flow advancesto S603.

In S603, the camera control unit 101 obtains the voltage value ofTYPE_IN, and stores this in a RAM region omitted from illustration.

Determination is made in S604 regarding whether or not the value ofTYPE_IN stored in S603 is within the range of 0x0080 or above and 0x017For below. If Yes is returned in S604, the camera control unit 101determines that the lens apparatus that has been mounted is the lensapparatus 200. In this case, the flow advances to S605.

In S605, the camera control unit 101 controls the power source switchingunit 104 so that the power supply voltage supplied to the firstcommunication interface unit 102 a is 3.0 V.

Thereafter, supply of power source to the VDD terminal 1001 by the powersource unit 103 is started in S606, and communication with the lensapparatus 200 by the first communication is started in S607.

On the other hand, in a case where No is returned in S604, the flowadvances to S608, where determination is made whether or not the valueof TYPE_IN stored in S603 is within the range of 0x0180 or above and0x02FF or below. If Yes is returned in S608, the camera control unit 101determines that the lens apparatus that has been mounted is the lensapparatus 300. In this case, the flow advances to S609.

In S609, the camera control unit 101 controls the power source switchingunit 104 so that the power supply voltage supplied to the firstcommunication interface unit 102 a is 5.0 V.

Thereafter, power source supply to the VDD terminal 1001 by the powersource unit 103 is started in S610, and in S611 the first communicationwith the lens apparatus 300 is started.

On the other hand, in a case where No is returned in S608, the flowadvances to S612. In this case, the camera control unit 101 determinesthat the accessory device that has been mounted is an accessory devicethat the camera body 100 cannot control, or that an abnormality isoccurring in the mounting state, and the flow advances to S613.

In S613, the camera control unit 101 does not perform communication withthe accessory, and makes a display on a display unit, omitted fromillustration, that is provided to the camera body 100, to the effectthat a connection error has occurred.

Determination of whether or not the power source of the camera body 100has been turned off, by an operation of the power switch of the camerabody 100, is made in S614. If determination is made that the powerswitch has been turned off, processing is performed to turn the powersource off. Otherwise, the flow advances to S615.

In S615, the camera control unit 101 reads in the voltage value at theMIF_IN terminal, and stores this in a RAM region that is omitted fromillustration.

In S616, determination is made regarding whether the voltage value ofMIF_IN stored in S615 is equivalent to a High level. If the voltagevalue of MIF_IN is High, determination is made that the lens apparatuswhich had been mounted to the camera body 100 has been detached. On theother hand, in a case where the voltage value of MIF_IN is Low,determination is made that the lens apparatus remains mounted, and theflow returns to S614.

In S617, the camera control unit 101 stops communication with the lensapparatus, and in S618 supply of power source to the VDD terminal 1001by the power source unit 103 is stopped. Thereafter, the flow advancesto S601.

Next, communication performed between the camera body 100 and anaccessory device mounted to the camera body 100 will be described.First, the first communication will be described. The firstcommunication is one type of communication performed between the camerabody 100 and a lens apparatus mounted to the camera body 100. The firstcommunication is performed using the LCLK terminals, DCL terminal, andDLC terminals. Further, the first communication is carried out using aclock-synchronous serial communication method. Note that the firstcommunication may be performed using an asynchronous serialcommunication method. It that case, the LCLK terminal is used as aterminal to notify the lens apparatus of a data transmission requestfrom the camera body 100.

The lens apparatus 200 and lens apparatus 300 both handle the firstcommunication. However, the communication voltage for the firstcommunication differs between the lens apparatus 200 and the lensapparatus 300, as described earlier.

The camera body 100 transmits a control command for controlling the lensapparatus, to the lens apparatus by the first communication. The controlcommand includes commands for driving the driving units (omitted fromillustration) of the lens apparatus. Examples of driving units of thelens apparatus include a focus lens, zoom lens, and diaphragm.

The lens apparatus that has received the control command transmitted bythe first communication performs operation in accordance with thecommand. In response to the control command, the lens apparatustransmits information relating to the state of itself (stateinformation) to the camera body 100, by the first communication.Information relating to state as used here includes information relatingto position of focus lens, focal length, and aperture value. Thus, thefirst communication is communication primarily used for controlling thelens apparatus.

Next, the second communication will be described. The secondcommunication is a type of communication performed between the camerabody 100 and the lens apparatus 200 mounted to the camera body 100, andis asynchronous communication performed using the DLC2 terminals 1009and 2009. Note that the second communication is not performed when thelens apparatus 300 is mounted to the camera body 100, since the lensapparatus 300 does not have a DLC2 terminal. Accordingly, the DLC2terminal 1009 is not used in a case where the lens apparatus 300 ismounted to the camera body 100.

In the second communication, the lens apparatus 200 serves as thecommunication master, and transmits the optical data such as theposition of the focus lens, the position of the zoom lens, aperturevalue, state of the image stabilization lens, and so forth, at the lensapparatus 200, to the camera body 100. The type and order of data thatthe lens apparatus 200 transmits to the camera body 100 using the secondcommunication is specified by the camera body 100 using the firstcommunication.

Now, the flow of the second communication will be described withreference to FIG. 9. The flowchart in FIG. 9 starts from the timing atwhich imaging control is started. Note that steps are represented by Sin the flowchart.

In S1401, the camera body 100 transmits to the lens apparatus 200 astart request requesting start of the second communication, using thefirst communication. The start request transmitted in S1401 includesregistration communication commands in which the type of data that thecamera body 100 desires to receive from the lens apparatus 200 using thesecond communication, and the order of reception, are registeredbeforehand.

The lens apparatus 200 receives the start request from the camera body100 in S1411. In S1412, the lens apparatus 200 generates the types ofdata specified by the registration communication command included in thestart request, in the specified order.

In S1413, the lens apparatus 200 transmits the data generated in S1412to the camera body 100 using the second communication. That is to say,the lens apparatus 200 transmits the data generated in S1412 to thecamera body 100 using the DLC2 terminal 2009.

The camera body 100 receives the data transmitted from the lensapparatus 200 by second communication in S1402.

In a case where imaging control is started again after S1402 or S1413,the control illustrated in FIG. 9 is started again.

Thus, the start request for the second communication is made by thefirst communication, and transmission of data from the lens apparatus200 to the camera body 100 by the second communication is performedusing the DLC2 terminal 2009. Accordingly, providing the DLC2 terminal2009 separate from the electric contacts used for first communication,and performing the second communication, enables optical data to betransmitted from the lens apparatus 200 to the camera body 100 withoutinterfering with other communication that needs to be performed by thefirst communication. It should be noted that the second communicationcannot be performed if the first communication has not been established,since the start request for the second communication is given using thefirst communication.

Next, the third communication will be described. The third communicationis communication performed among the lens apparatus 200, intermediateaccessory device 400, intermediate accessory device 500, and camera body100, and is asynchronous communication carried out using the DCAterminals and CS terminals.

As described earlier, the lens apparatus 300 does not have a DCAterminal or CS terminal, and so the camera body 100 and lens apparatus300 do not perform the third communication in a case where the lensapparatus 300 is mounted to the camera body 100 via the intermediateaccessory device 400. However, in this case, the camera body 100 and theintermediate accessory device 400 may perform the third communication.

In the third communication, the communication master is the camera body100 and the communication slaves are the lens apparatus 200,intermediate accessory device 400, and intermediate accessory device500. Although FIGS. 5A and 5B illustrate only one intermediate accessorydevice 500 being mounted between the camera body 100 and lens apparatus200, there are cases where multiple intermediate accessory devices aremounted between the camera body 100 and lens apparatus 200. Accordingly,in the third communication, there are cases where multiple communicationslaves are serially connected to one communication master. Accordingly,in the third communication, communication can be performed in abroadcast communication mode where the camera body 100 transmits signalsto the multiple accessories at the same time, and peer-to-peer (P2P)mode where a particular slave is specified and communication isperformed.

The DCA terminals both function as terminals to transmit/receive data inthe broadcast communication mode and P2P mode in the thirdcommunication. On the other hand, the functions of the CS terminalsdiffer between the broadcast communication mode and P2P mode.Hereinafter, the functions of the CS terminals in the broadcastcommunication mode and P2P mode will be described, by way of an exampleof a case where the lens apparatus 200 is mounted to the camera body 100via the intermediate accessory device 500.

FIG. 10 illustrates communication control timing in broadcastcommunication exchanged among the camera control unit 101, lens controlunit 201, and accessory control unit 501. The CS terminals of the cameracontrol unit 101, lens control unit 201, and accessory control unit 501,are expressed as CS (camera), CS (lens), and CS (accessory). Also, theoutputs of the DCA terminals of the camera control unit 101, lenscontrol unit 201, and accessory control unit 501, are expressed as DCA(camera), DCA (lens), and DCA (accessory), respectively. The signalwaveform of a signal line made up of the CS terminals (CS signal line)and signal waveform of a signal line made up of the DCA terminals (DCAsignal line) are respectively denoted by CS and DCA. FIG. 10 illustratesa case of the accessory control unit 501 performing broadcastcommunication to the camera control unit 101 and lens control unit 201in response to broadcast communication performed from the camera controlunit 101 to the lens control unit 201 and accessory control unit 501.

At the timing of (1) shown in FIG. 10, the camera control unit 101 thatis the communication master outputs Low to the CS terminals, to notifythe lens control unit 201 and accessory control unit 501 that arecommunication slaves, that broadcast communication is going to bestarted. Next, at the timing of (2) shown in FIG. 10, the camera controlunit 101 outputs data to be transmitted, to the DCA terminals.

Upon detecting a start bit ST of the signal input from their DCAterminals at the timing of (3) in FIG. 10, the lens control unit 201 andaccessory control unit 501 start Low output to their CS terminals. Notethat at this point, the camera control unit 101 is already outputtingLow to the CS terminal at the timing of (1), so the level on the CSsignal line is unchanged.

When output of the data to be transmitted has been completed up to thestop bit SP at the timing of (4) in FIG. 10, the camera control unit 101releases the Low output to the CS terminal at the timing of (5). On theother hand, upon having received up to the stop bit SP, the lens controlunit 201 and accessory control unit 501 perform analysis of the receiveddata and internal processing relating to the received data. In a casewhere the internal processing has been completed, and preparation hasbeen made to receive the next data, the lens control unit 201 andaccessory control unit 501 release the Low output to their CS terminalsat the timing of (6) and (7), respectively.

Now, the amount of time required for the analysis of the received dataand internal processing relating to the received data differs dependingon the processing abilities of the individual control units.Accordingly, each control unit needs to comprehend the timing at whichthe internal processing relating to the received data has been completedat all of the other microprocessors.

Note that the CS terminals in the present embodiment are open-typeoutput terminals, as mentioned earlier. Accordingly, when all of thecamera control unit 101, lens control unit 201, and accessory controlunit 501 release the Low output to their respective CS terminals, thelevel on the CS signal line goes to High. That is to say, the controlunits that are involved in the broadcast communication can judge thatpreparation for the next communication has been made at the othercontrol units, by confirming that the level of the CS signals line hasgone to High, and accordingly can appropriately perform the nextcommunication.

At the timing of (8), the accessory control unit 501 starts Low outputto the CS terminal, to notify the camera control unit 101 and lenscontrol unit 201 that broadcast communication is going to be started.Next, the accessory control unit 501 outputs data to be transmitted tothe DCA terminal at the timing of (9).

Upon having detected the start bit ST input from their DCA terminals,the camera control unit 101 and lens control unit 201 start Low outputto their CS terminals at the timing of (10). Note that the accessorycontrol unit 501 has already started Low output to the CS terminal atthis point, so the level of the CS signal line is unchanged. Aftercompleting output of the stop bit SP at the timing of (11), theaccessory control unit 501 releases the Low output to the CS terminal atthe timing of (12).

After having received the stop bit SP input from their DCA terminals,the camera control unit 101 and lens control unit 201 perform analysisof the received data and internal processing associated with thereceived data. After preparation to receive the next data has been made,the camera control unit 101 and lens control unit 201 release the Lowoutput to their CS terminals, at the timing of (13) and (14),respectively. Thus, the CS terminals serve in broadcast communication tomake notification of timing to start broadcast communication and timingthat preparation for reception has been completed at allmicroprocessors, by change in voltage.

Next, the functions to the CS terminal in P2P communication will bedescribed. FIG. 11 illustrates communication timing on P2P communicationexchanged between the camera control unit 101, lens control unit 201,and accessory control unit 501. An example will be described here whereone byte worth of data is transmitted from the camera control unit 101to the lens control unit 201, and the lens control unit 201 transmitstwo bytes worth of data to the camera control unit 101 in response tothat data.

First, the camera control unit 101 uses the DCA terminal to transmit acommand to the lens control unit 201 to cause particular data to betransmitted, at the timing of (1) shown in FIG. 11. After the timing of(2) where output has been completed up to the stop bit SP, the cameracontrol unit 101 starts Low output to the CS terminal at the timing of(3). The camera control unit 101 performs preparation to receive datawhile outputting Low to the CS terminal, and at the timing of (4) wherepreparation has been made, releases the Low output to the CS terminal.

On the other hand, after having detected the Low signal at the CSterminal output by the camera control unit 101, the lens control unit201 analyzes the command received from the camera control unit 101, andperforms internal processing relating to this command. After havingconfirmed that the Low output of the CS terminal has been released, thelens control unit 201 transmits data, corresponding to the commandreceived from the camera control unit 101, from the DCA terminal. Afterthe timing of (6) where output has been completed up to output of thestop bit SP of the second byte, the lens control unit 201 starts Lowoutput to the CS terminal at the timing of (7).

Subsequently, the lens control unit 201 releases Low output to the CSterminal at the timing of (8) where preparation for reception of thenext data has been made. Note that the accessory control unit 501, whichhas not been specified as a communication party in the P2P communicationis not involved in operation of the CS signal line and DCA signal linewhatsoever. Thus, in the P2P mode, the CS terminals notify the timing atwhich data transmission has been completed at the data transmitting sidedevice, and the timing at which preparation for data reception has beencompleted at the data receiving side device, by change in voltage value.

As described above, in the third communication, the functions of the CSterminals are different between the broadcast communication mode and theP2P mode. This realizes the broadcast communication mode and the P2Pmode using only two signal lines. Further, transmission/reception ofdata in the third communication is performed by the DCA terminals ofwhich the input/output interface is a CMOS type. Accordingly, high-speedcommunication can be realized even if the input/output interface of theCS terminals, which are used simply for notification of various types oftimings in the third communication, are of the open type.

Next, communication voltage of the first through third communicationwill be described. In a case where the lens apparatus 200 is mounted tothe camera body 100, the first communication, the second communication,and the third communication can be performed, as described earlier. Onthe other hand, in a case where the lens apparatus 300 is mounted to thecamera body 100, the first communication and the third communication canbe performed. That is to say, the case where the lens apparatus 200 ismounted to the camera body 100 has more types of communication to beperformed as compared to a case where the lens apparatus 300 has beenmounted. Accordingly, the communication voltage in the case where thelens apparatus 200 is mounted to the camera body 100 is preferably lowerfrom the perspective of reducing power consumption. To this end, thecommunication voltage for the first communication in a case where thelens apparatus 200 has been mounted (3.0 V) is set to be lower than thecommunication voltage in a case where the lens apparatus 300 has beenmounted (5.0 V).

Also, the configuration of the second/third communication interface unit202 b can be simplified by the communication voltage of the thirdcommunication being the same between a case where the lens apparatus 200has been mounted and a case where the lens apparatus 300 has beenmounted. At this time, the communication voltage of the thirdcommunication preferably is equal to the lower of the communicationvoltage of the first communication in a case where the lens apparatus200 has been mounted and the communication voltage of the firstcommunication in a case where the lens apparatus 300 has been mounted.Accordingly, the power consumption for performing the thirdcommunication can be reduced.

Next, the array order of the electric contacts will be described, takinginto consideration the circuit configurations and roles of the electriccontacts of the camera body 100, lens apparatus 200, and intermediateaccessory devices 400 and 500 into consideration. As described above,drive control and obtaining state information of the lens apparatus 200and lens apparatus 300 is performed by the first communication.Accordingly, even if the second communication and the thirdcommunication cannot be performed due to faulty contact among theelectric contacts, primary control of the lens apparatus 200 and lensapparatus 300 can be performed as long as the first communication hasbeen established. Conversely, if the first communication becomesunavailable due to faulty contact among the electric contacts, thecamera body 100 can no longer control the lens apparatus 200 or lensapparatus 300. Accordingly, it can be said that the electric contactsused for the first communication are more important as compared to theelectric contacts used for the second communication and the thirdcommunication.

Accordingly, the electric contacts are arrayed in the present embodimentsuch that the amount of wear of the first camera-side electric contactgroup due to mounting and detaching accessory devices is smaller thanthe electric contacts 1009 through 1011 used for the secondcommunication or the third communication. This will be described withreference to FIGS. 4A and 4B.

When mounting the lens apparatus 200 to the camera body 100, the lensapparatus 200 moves (rotates) from the position illustrated in FIG. 4Bto the position illustrated in FIG. 4A, with respect to the camera body100. At this time, each of the electric contacts held by the camera-sidecontact holding member 154 come into contact with the electric contactsheld by the accessory-side contact holding member 254 at least once. Thegreater the number of times that an electric contact comes into contactwith the electric contacts held at the accessory-side contact holdingmember 254, the greater the amount of wear is.

The timings at which the electric contacts 1001 through 1012 start tocome into contact with the electric contacts held by the accessory-sidecontact holding member 254 during a period from starting to mount thelens apparatus 200 to the camera body 100 up to the mounting beingcompleted differ for each. For example, the DGND terminal 1012 comesinto contact with an electric contact held at the accessory-side contactholding member 254 the earliest of all the electric contacts 1001through 1012 when mounting the lens apparatus 200 to the camera body100. The DGND terminal 1012 comes into contact with the electriccontacts 2005 through 2012 until mounting of the lens apparatus 200 iscomplete, so the number of times that the DGND terminal 1012 comes intocontact with electric contacts held at the accessory-side contactholding member 254 is eight. On the other hand, the CS terminal 1011that comes into contact with the electric contacts held at theaccessory-side contact holding member 254 next after the DGND terminal1012 comes into contact with the electric contacts 2005 through 2011until mounting of the lens apparatus 200 is complete, so the number oftimes that the CS terminal 1011 comes into contact with electriccontacts held at the accessory-side contact holding member 254 is seven,which is less than that of the DGND terminal 1012. Thus, when mountingthe lens apparatus 200 to the camera body 100, the earlier the timing ofan electric contact starting to come into contact with the electriccontacts held by the accessory-side contact holding member 254 is, thegreater the number of times of contact with the electric contacts heldby the accessory-side contact holding member 254 is.

In the array of electric contacts according to the present embodiment,when mounting the lens apparatus 200, the electric contacts 1009 through1011 that are used for the second or third communication come intocontact with electric contacts provided at the accessory-side contactholding member 254 before the electric contacts 1006 through 1008 thatare used for the first communication. According to this array of theelectric contacts, the amount of wear of the first camera-side electriccontact group used for the first communication can be reduced ascompared to that of the electric contacts 1009 through 1011 that areused for the second or third communication. Thus, occurrence of faultycommunication due to wear of the electric contacts can be reduced.

Note that the electric contacts 2006 through 2008, which are the firstlens-side electric contact group, can be said to be disposed at aposition where the amount of wear when mounting and detaching the lensapparatus 200 to and from the camera body 100 is greater as compared tothe electric contacts 2009 through 2011. However, multiple types ofcamera accessories are mounted to the camera body 100 as illustrated inFIG. 1, and so the amount of wear of the electric contacts at the lensapparatus 200 is smaller than that at the camera body 100. Accordingly,the electric contacts are arrayed in the present embodiment so that theamount of wear of the first camera-side electric contact group issmaller, giving consideration to the electric contacts at the camerabody 100 side where the electric contacts wear more readily.

Next, the order of the array of the DGND terminal, CS terminal, and DCAterminal will be described with reference to FIGS. 12A and 12B. First, acase will be considered as a comparative example, in which the DCAterminal is disposed adjacent to the DGND terminal. The peripheralcircuits of the CS terminal, DCA terminal, and DGND terminal in thiscase are illustrated in FIG. 12A. The DCA terminal is a CMOS typeinput/output interface terminal, as described earlier. In a case wherethe DGND terminal and DCA terminal are short-circuited due to anelectroconductive foreign substance becoming lodged between the camerabody and the accessory device in FIG. 12A or the like, when High levelis output to the DCA terminal, a large current will flow from the DCAterminal toward the DGND terminal. This is because the resistance of theCMOS type interface is low when outputting High level. In this case, agreat current may flow into the accessory device and the camera bodythat is performing the third communication, and affect the internalcircuits.

On the other hand, the CS terminal is disposed between the DCA terminaland DGND terminal in the present embodiment. FIG. 12B illustrates theperipheral circuits of the CS terminal, DCA terminal, and DGND terminalof the camera body 100 and the lens apparatus 200 serving as anaccessory device according to the present embodiment. As describedabove, the CS terminal is an open type output terminal. Accordingly,even if the DGND terminal and CS terminal short-circuit in FIG. 12B,only a small current will flow to the DGND terminal. This is because theCS terminal is pulled up to the power source potential via a resistor.Thus, this arrangement where the electric contact adjacent to the DGNDterminal is the CS terminal which is an open type output terminalenables electrical effects on the internal circuits of the accessorydevice and camera body 100 to be reduced in a case where electriccontacts are connected to each other unintentionally.

The DLC2 terminal is disposed adjacent to the electric contact groupused for the first communication in the present embodiment. That is tosay, the DLC2 terminal is disposed adjacent to the LCLK terminal. Thereason for this will be described by way of comparison with a case wherethe CS terminal or DCA terminal used for the first communication isdisposed. Assumption will be made in the following that the lensapparatus 300 has been mounted to the camera body via an intermediateaccessory device that is capable of the third communication with thecamera body. Accordingly, the communication voltage of the firstcommunication is 5.0 V, the communication voltage of the thirdcommunication is 3.0 V, and second communication is not performed.

FIG. 13A illustrates the peripheral circuits of the LCLK terminal and CSterminal in a case where the CS terminal is disposed adjacent to theLCLK terminal. The LCLK terminal is pulled up to 5.0 V, which is thecommunication voltage for first communication, at each of the camerabody and lens apparatus 300. On the other hand, the CS terminal ispulled up to 3.0 V, which is the communication voltage for the thirdcommunication at the camera body and the intermediate accessory device.Now, if an electroconductive foreign substance 90 becomes lodged betweenthe LCLK terminal and the CS terminal, and the LCLK terminal and the CSterminal are short-circuited, voltage exceeding 3.0 V may be applied tothe CS terminal. At this time, voltage exceeding the operating voltage(3.0 V) will be applied to the second/third communication interface unitof the camera body and the accessory control unit of the intermediateaccessory device, which is undesirable.

FIG. 13B illustrates the peripheral circuits of the LCLK terminal andDCA terminal in a case where the DCA terminal is disposed adjacent tothe LCLK terminal. The DCA terminal is pulled up to 3.0 V, which is thecommunication voltage for the third communication at the camera body andthe intermediate accessory device. Now, if an electroconductive foreignsubstance 90 becomes lodged between the LCLK terminal and the DCAterminal, and the LCLK terminal and the DCA terminal areshort-circuited, voltage exceeding 3.0 V may be applied to the DCAterminal. At this time, voltage exceeding the operating voltage (3.0 V)will be applied to the second/third communication interface unit of thecamera body and the accessory control unit of the intermediate accessorydevice, which is undesirable.

FIG. 13C illustrates the peripheral circuits of the LCLK terminal andDLC2 terminal in a case where the lens apparatus 300 is mounted to thecamera body 100 via the intermediate accessory device 400. The secondcommunication is not performed at this time, so the DLC2 terminal is notused. Accordingly, even if the LCLK terminal and the DLC2 terminal areshort-circuited, the internal circuits of the camera body 100 andintermediate accessory device 400 are not readily affected in thepresent embodiment.

Note that in a case where the lens apparatus 200 is mounted to thecamera body 100, the second communication is performed, but thecommunication voltage of the first communication and the secondcommunication is 3.0 V for both. Accordingly, even in a case where theLCLK terminal and DLC2 terminal are short-circuited, excessive voltagewill not be applied to the internal circuits of the camera body 100 orlens apparatus 200. According to the above, it can be said the electriccontact adjacent to the electric contact group used for firstcommunication is the DLC2 terminal not used when the lens apparatus 300is mounted.

Further, in a case where the lens apparatus 200 is mounted to the camerabody 100, the second communication and the third communication can beperformed at the same time. In this case, even if the DLC2 terminal andthe DCA terminal are short-circuited, excessive voltage will not beapplied to the internal circuits of the camera body 100 or lensapparatus 200, since the communication voltage for the secondcommunication and the third communication is 3.0 V. Accordingly, the CSterminal or DCA terminal is preferably adjacent to the DLC2 terminal.Also, the DLC2 terminal is disposed between the LCLK terminal and the CSterminal or DCA terminal in this case, so short-circuiting of the LCLKterminal and the CS terminal or DCA terminal can be made to occur lessreadily. Accordingly, short-circuiting among electric contacts thatperform communication at different communication voltages can beprevented when mounting the lens apparatus 300 to the camera body 100via the intermediate accessory device 400.

Although a preferred embodiment of the present invention has beendescribed, the present invention is not restricted to this embodiment,and various modifications and alterations may be made within the scopeof the essence thereof. Although an example has been described in thepresent embodiment where the camera body 100 has electric contacts 1009through 1011 as a second camera-side electric contact group, and secondcommunication and third communication can be performed with mountedaccessory devices, this is not restrictive. For example, the camera body100 may have just the electric contacts 1010 and 1011 as the secondcamera-side electric contact group. In this case, the camera body 100will not have the electric contact 1009. Accordingly, the camera body100 will not be able to handle the above-described second communication.Conversely, the camera body 100 may have just the electric contact 1009as the second camera-side electric contact group. In this case, thecamera body 100 will not have the electric contacts 1010 and 1011.Accordingly, the camera body 100 will not be able to handle theabove-described third communication.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. An imaging apparatus to which a lens apparatus isdetachably mountable, the imaging apparatus comprising: a mount unit;and a contact holding member provided to the mount unit where aplurality of electric contacts are arrayed, wherein the plurality ofelectric contacts include: a first power contact configured to supplyfirst power, a second power contact configured to supply second power, afirst electric contact group configured to be used to perform firstcommunication, and a second electric contact group configured to be usedto perform communication that is different from the first communication,and wherein, where a direction of rotation of the lens apparatus withrespect to the imaging apparatus when mounting the lens apparatus to theimaging apparatus directly is a first direction, the second electriccontact group, the first electric contact group, the first power contactand the second power contact are arrayed in the order of the secondelectric contact group, the first electric contact group, the secondpower contact and the first power contact in the first direction.
 2. Theimaging apparatus according to claim 1, wherein the imaging apparatustransmits a control command to control the mounted lens apparatus, usingthe first electric contact group.
 3. The imaging apparatus according toclaim 1, wherein the second electric contact group includes an electriccontact configured to be capable of transmission and reception of data,and an electric contact configured to perform notification of timingrelating to communication using the second electric contact group. 4.The imaging apparatus according to claim 3, wherein, in a state where aplurality of accessories are mounted to the imaging apparatus, theimaging apparatus performs communication with the plurality ofaccessories using the second electric contact group.
 5. The imagingapparatus according to claim 4, wherein the communication using thesecond electric contact group is broadcast communication where data istransmitted from one of the plurality of accessories and the imagingapparatus to all the other of the plurality of accessories and theimaging apparatus, and wherein the timing includes a timing of startingthe broadcast communication.
 6. The imaging apparatus according to claim4, wherein the communication using the second electric contact group isbroadcast communication where data is transmitted from one of theplurality of accessories and the imaging apparatus to all the other ofthe plurality of accessories and the imaging apparatus, and wherein thetiming includes a timing of completing preparation for reception of dataat all the other of the plurality of accessories and the imagingapparatus.
 7. The imaging apparatus according to claim 4, wherein thecommunication using the second electric contact group is peer-to-peercommunication performed between one of the plurality of accessories andthe imaging apparatus, and wherein the timing includes a timing ofcompleting transmission of data at the side of the one of the pluralityof accessories or the imaging apparatus transmitting data in thepeer-to-peer communication.
 8. The imaging apparatus according to claim4, wherein the communication using the second electric contact group ispeer-to-peer communication performed between one of the plurality ofaccessories and the imaging apparatus, and wherein the timing includes atiming of completing preparation for reception of data at the side ofthe one of the plurality of accessories or the imaging apparatusreceiving data in the peer-to-peer communication.
 9. The imagingapparatus according to claim 1, wherein the second electric contactgroup includes an electric contact capable of receiving data transmittedfrom the lens apparatus, and wherein the data transmitted from the lensapparatus using the second electric contact group is data specified bythe imaging apparatus by communication using the first electric contactgroup.
 10. The imaging apparatus according to claim 1, wherein the firstelectric contact group includes an electric contact configured to becapable of outputting a clock signal, an electric contact configured tobe capable of transmitting data synchronously with the clock signal, andan electric contact configured to be capable of receiving datatransmitted synchronously with the clock signal.
 11. The imagingapparatus according to claim 1, wherein the plurality of electriccontacts include, disposed on the opposite side of the first electriccontact group from the second electric contact group: an electriccontact used to determine whether or not a lens apparatus is mounted tothe imaging apparatus, an electric contact used to determine a type oflens apparatus mounted to the imaging apparatus, and an electric contactconfigured to set a ground level of the second power.
 12. The imagingapparatus according to claim 1, wherein the imaging apparatus is capableof mounting any one of lens apparatuses including a first lens apparatusand a second lens apparatus, wherein the imaging apparatus is configuredto perform communication using the first electric contact group withboth of the first lens apparatus and the second lens apparatus, andwherein the imaging apparatus is configured to perform communicationusing the second electric contact group with the second lens apparatusbut is configured not to perform communication using the second electriccontact group with the first lens apparatus.
 13. The imaging apparatusaccording to claim 12, wherein the first lens apparatus is configured tobe mounted to the imaging apparatus only via an intermediate accessory.14. The imaging apparatus according to claim 1, wherein the contactholding member has two tiers each of which holds electric contactsincluded in the plurality of electric contacts, wherein the firstelectric contact group and the second electric contact group are held onone of the two tiers and the first power contact and the second powercontact are held on the other of the two tiers, and wherein theplurality of electric contacts include an electric contact used todetermine whether or not a lens apparatus is mounted to the imagingapparatus, at a location on the same tier with the first electriccontact group and opposite from the second electric contact group inbetween the first electric contact group.
 15. The imaging apparatusaccording to claim 1, wherein the contact holding member has two tierseach of which holds electric contacts included in the plurality ofelectric contacts, wherein the first electric contact group and thesecond electric contact group are held on one of the two tiers and thefirst power contact and the second power contact are held on the otherof the two tiers, and wherein the plurality of electric contacts includean electric contact used to determine a type of lens apparatus mountedto the imaging apparatus at a location on the same tier with the firstpower contact and the second power contact.
 16. An accessory detachablymountable to an imaging apparatus, the accessory comprising: a mountunit; and a contact holding member provided on the mount unit where aplurality of electric contacts of the accessory are arrayed, wherein theplurality of electric contacts includes: a first power contactconfigured to receive first power, a second power contact configured toreceive second power, a third electric contact group configured to beused to perform first communication, and wherein, where a direction ofrotation of the accessory when mounting the accessory is a firstdirection, the third electric contact group, the first power contact andthe second power contact are arrayed in the order of the third electriccontact group, the second power contact and the first power contact inthe first direction.
 17. The accessory according to claim 16, whereinthe imaging apparatus is capable of mounting any one of lens apparatusesincluding a first lens apparatus and a second lens apparatus, whereinthe imaging apparatus includes a plurality of electric contactsincluding: a first electric contact group used to perform the firstcommunication with at least one of accessory mounted to the imagingapparatus, and a second electric contact group used to performcommunication that is different from the first communication with atleast one of accessory mounted to the imaging apparatus, wherein theimaging apparatus is configured to perform communication using the firstelectric contact group with both of the first lens apparatus and thesecond lens apparatus, and wherein the imaging apparatus is configuredto perform communication using the second electric contact group withthe second lens apparatus but is configured not to perform communicationusing the second electric contact group with the first lens apparatus.18. The accessory according to claim 17, wherein the first lensapparatus is configured to be mounted to the imaging apparatus only viaan intermediate accessory.
 19. The accessory according to claim 16,wherein the contact holding member has two tiers each of which holdselectric contacts included in the plurality of electric contacts,wherein the third electric contact group is held on one of the two tiersand the first power contact and the second power contact are held on theother of the two tiers, and wherein the plurality of electric contactsof the accessory include: an electric contact used for indicating that alens apparatus is mounted to the imaging apparatus at a location on thesame tier with the third electric contact group, and an electric contactused for indicating a type of a mounted lens apparatus at a location onthe same tier with the first power contact and the second power contact.20. The accessory according to claim 16, wherein the accessory is a lensapparatus having an optical system.
 21. The accessory according to claim16, wherein the accessory is an intermediate accessory detachablymountable between the imaging apparatus and a lens apparatus.
 22. Acamera system, comprising: an imaging apparatus; and an accessoryconfigured to be detachably mountable to the imaging apparatus, whereinthe imaging apparatus includes a first mount unit and a contact holdingmember provided to the mount unit where a plurality of electric contactsare arrayed, the plurality of electric contacts of the imaging apparatusincluding: a first power contact used to supply first power, a secondpower contact used to supply second power, a first electric contactgroup used to perform first communication with at least one of accessorymounted to the imaging apparatus, and a second electric contact groupused to perform communication that is different from the firstcommunication with at least one of accessory mounted to the imagingapparatus, wherein the accessory includes a second mount unit capable ofcoupling with the first mount unit, and where a plurality of electriccontacts are arrayed, the plurality of electric contacts of theaccessory including: a third electric contact group made up of electriccontacts that comes into contact with electric contacts included in thefirst electric contact group in a state where the accessory is mountedto the imaging apparatus directly, and wherein, where a direction ofrotation of the accessory with respect to the imaging apparatus whenmounting the accessory directly to the imaging apparatus is a firstdirection, the second electric contact group and the first electriccontact group are arrayed in the order of the second electric contactgroup and the first electric contact group in the first direction. 23.The camera system according to claim 22, wherein the imaging apparatusis capable of mounting any one of lens apparatuses including a firstlens apparatus and a second lens apparatus, wherein the imagingapparatus is configured to perform communication using the firstelectric contact group with both of the first lens apparatus and thesecond lens apparatus, and wherein the imaging apparatus is configuredto perform communication using the second electric contact group withthe second lens apparatus but is configured not to perform communicationusing the second electric contact group with the first lens apparatus.